Polymer, Vol.144, 150-158, 2018
Understanding reversible Maxwellian electroactuation in a 3M VHB dielectric elastomer with prestrain
Dielectric elastomers can undergo a large strain under a high driving electric field; however, significant creep is observed due to the viscoelasticity under the Maxwellian pressure. In this work, dielectric properties of a VHB 4905 tape with different prestrains were studied using low-field broadband dielectric spectroscopy and high-field electric displacement-electric field loop measurements. The dielectric constant first increased (below 200% prestrain) and then decreased (above 200% prestrain) upon increasing the prestrain. Electroactuation of prestrained VHB films was studied using both direct current (DC) and alternating current (AC) driving fields. Only the AC actuation method could be used to subtract the creep contribution and obtain reversible Maxwellian actuation. In addition to removing the boundary constraint, prestrain had more influence on the actuation property of VHB. The Young's modulus reached the minimum level (similar to 0.05 MPa) between 100% and 400% areal prestrain, and increasing the prestrain could enhance electroactuation. Above 500% prestrain, the electroactuation started to decrease because of significant strain-hardening in the sample. Different nonlinear mechanical models were used to fit the experimental data of electroactuation. This study provides a viable standard for the future investigation of reversible Maxwellian actuation in various dielectric elastomers. (C) 2018 Elsevier Ltd. All rights reserved.